Why non-towered airports are a safety question

How a non-towered airport works

At an airport without an operating tower, there is no one issuing clearances. Pilots follow standard traffic patterns and announce their position and intentions on the common traffic advisory frequency (CTAF), as set out in the FAA's Aeronautical Information Manual and Advisory Circular 90-66, Non-Towered Airport Flight Operations. Each pilot builds a mental picture of the traffic from what they hear and see.

That works when everyone is on frequency, says the right thing at the right time, and is where they say they are. The gap is in the cases where they are not.

Where the gap is

No one sequences the traffic. Arrivals, departures, training circuits and straight-in approaches are sorted out between pilots, in real time, on one shared frequency.
Radios are not always required. Aircraft without a radio can legally use many non-towered airports, and a radio call can be missed, blocked or made on the wrong frequency.
Mixed traffic. Students, business aircraft, helicopters, gliders, skydiving and agricultural flights can share the same pattern, at different speeds.
No one is watching the runway. A vehicle, an animal or an aircraft on the runway is spotted only by the pilot about to use it.
Night and weather. In darkness and low visibility, seeing other traffic gets harder exactly when it matters most.

Check the record for your own airport

Rather than rely on national averages, look at your own field. The NTSB's CAROL database lets you search accident and incident investigations by airport, and the FAA's runway safety pages cover runway incursions and how airports reduce them.

What a digital tower changes for pilots

A controller sequences arrivals and departures and issues clearances, instead of each pilot negotiating on CTAF.
Someone watches the runway: systems such as General Aviation's alert the controller when an incursion is detected.
Conflict alerts bring aircraft that are getting too close to the controller's attention.
A light gun lets the controller signal an aircraft without a working radio.
With General Aviation's system, no new cockpit equipment: standard VHF radios and transponders, with an optional companion app that shows the taxi route, the pattern entry and a transcript of each instruction.

What it changes for operators

Tower services without building a tower or recruiting controllers who live nearby.
A recorded picture of what happens on the field: General Aviation's control center keeps audio and video for 45 days.
A path to the traffic a tower can attract and support, from flight schools to business aviation.

What it does not change

Pilots still see and avoid. And when a digital tower is not providing service, for instance outside its published hours, the airport works as a non-towered field again, so pilots should check the hours and airspace in the FAA Chart Supplement before every flight.